Energy  Humans use varied energy resources  Most came from solar energy  Decomposition of plants, animals buried underground form fossil fuels Which are non- renewable?

How fossil fuels are formed  1. Plants and animals collect in layers of mud in a shallow sea  2. Layer is buried, heated, pressurized  3. Rock is bent, oil is trapped with natural gas above and water below

global energy sources global energy sources  Fossils fuels are non-renewable  88% is from fossil sources  Burning creates CO 2  Fossil fuels will someday run out

Past and future energy use

Which countries consume the most energy?

Alternative energy sources  Solar  Wind  Geothermal  Nuclear  Tidal  Hydroelectric  Biofuel  We are searching for other sources of energy  Renewable resources will not run out  Environmental impacts could be much less

Desert areas have potential for solar, geothermal power Coastal areas for wind generation and tidal power Renewable energy sources

Hydro- electric  Moving water turns turbines to generate electricity  Most rivers are already dammed  Causes problems for fish, downstream habitats

Reducing energy waste  All forms of energy generation waste energy  Power plants are only 35% efficient  We need to reduce our energy use and energy waste 157 mpg car

Review 1.Where does most energy for life come from? 2.Is oil a renewable resource? 3.How much energy does the US use compared to the world average?